Skip to content


Return to Blog »

Lighting – Let the Sun In!

We have heard so much about sun light not being good for us that we have missed the impact of natural light, in particular narrow spectrum blue light, and what it can do for our health and even well-being. We have also become energy efficient with lower artificial lighting levels inside that could adversely affect us as we age.

So how does natural light, in particular, narrow spectrum blue light correlate with health? There have been numerous studies which show having too small of an amount can cause a higher incidence of cancer – a study of night shift nurses shows a 20% higher incidence of breast cancer than their day shift peers. Same goes for prostrate cancer. The elderly who many times are restless sleepers are shown to have quicker sleep onset with a deeper and longer sleep when they receive more day time light. Even those with dementia have shown a stop to cognitive decline similar to medications without the side affects (although this does not stop the progressive cognitive worsening of the disease). And there is a lowering of blood pressure as well as increased resistance to colds, just to name a few.

If our eyes are closed we do not receive and synthesize the effects of this blue light. Likewise if we are blind, although if the blindness is caused by neurological issues we would still receive benefit since it is not the receptor that is damaged. If we are wearing sunglasses or in a building that has tinted windows we would receive the benefits since these only filter out light intensity, although some windows can filter out these light waves and the specifications should be reviewed. Likewise, some sunglasses might also filter out these light waves, but for the most part glazing and sun glasses just filter out light intensity.

So how does this work? Visible light enters our eyes thru rods and cones. Narrow spectrum blue light enters our eyes thru a similar receptor, but the signals connect thru the suprachiasmatic nucleus (SCN) which acts as our biological clock. If we have predominantly cool light during the day and warm light at night, we will have less of a disruption in our normal day/night cycles. This allows our body to produce the correct balance of day time alert transmitters and night time restorative hormones affecting our circadian rhythms. Quite a mouthful, but basically it affects a number of items related to our health and natural cycles.

This narrow spectrum blue light is not about the color but rather about the wave length of 450-500 nanometers (470 nm is optimum) – so a blue painted room has no effect nor does a light with a colored screen. Night lights might affect our circadian rhythms – if it is bright enough for us to see, it is bright enough to have an effect on our night time melatonin production. Marker lights, on the other hand, such as the controls on a range or light switch, do not produce enough light to have an affect.

As we age, we take in less light due to changes in the eye structure so we need more day time lighting, more intense or for longer periods, in order to compensate. Assisted living homes typically have lower light levels and nursing homes even lower yet, hence a more rapid decline. Studies have shown that when cool day light levels are increased during the day, residents rapidly respond with improved moods, better health, a lessening of functional limitations, and better sleep.

So what does this mean about our own environment whether young or old? Perhaps we should consider placing ourselves in environments where there is more natural light. If we are in rooms that are dark and gloomy we should consider upping the daytime light level. More light and more narrow spectrum blue light during the day leads to better night time sleep. And as numerous studies have shown over the last two decades, this in turn leads to all kinds of positive things regarding our health and well-being.

Be aware that your local City or County may have additional requirements that are more restrictive than the State or Federal requirements. Also, this article is an interpretation and opinion of the writer. It is meant as a summary – current original regulations should always be reviewed when making any decisions.

© 2013 Janis Kent, Architect, CASp